Neway cutters and seat concentricity

[AC sports]

Here's an example of what I mean. Seat cut with neways. Nice and shiny all round. I mark the seat with black ink and lap the valve to check seating. Result is in the picture. If I continue cutting it does the same thing.
Cutter is 45* as is valve in this instance.
I'd like to hear people's thoughts and experience with the neways.

[modok]

Oh.... yeah that's a concentricity problem, or it's just oval.
I don't like neways but some do, and maybe those guys have some hints for you.
If you'd like to discuss how to grind seats for cheap I've got a lot of ideas about that.
No reason you can't use BOTH, on the same pilots IMO, and it doesn't have to be expensive.

[ProPower engines]

Here's an example of what I mean. Seat cut with neways. Nice and shiny all round. I mark the seat with black ink and lap the valve to check seating. Result is in the picture. If I continue cutting it does the same thing.
Cutter is 45* as is valve in this instance.
I'd like to hear people's thoughts and experience with the neways.

This is always the same issue with the neway cutters. They were designed to touch up a good seat but even with the driver stand there is too many U joints to cause the cutter to go off center and the split pilots don't help the issue.

I started using sioux seat grinding stuff in the 70's and still have all that kit under the bench for special stuff that can't be done in the machines I have now.
The multi seat cutter systems like serdi or sunnen and others do a much better job because the head id rigidly held in place
and the cutter is also rigidly locked in place by air clamp system.
Guys use stone to just finish seats because they are fanatical about seat finish and sealing but use a seat cutter machine to get the job done to that point. I use a stone at times to finish seats because I want perfection as do most guys but there is that myth about how good it has to be. and some guys don't believe it makes a difference to be that perfect cause they wear in anyway. Not really true.
The OEM stuff used an interference valve job by using 1 degree difference between the valve and seat angles so they would beat themselves together over time and while it does work performance is lost from leaky valve seats.


Using stones to do a valve job is just fine as long as the stone holders are not worn out and the pilots are not bent. There has been many championship winning engines build using stones to do the seats it just takes much longer to achieve the same results.
But as mentioned a million times before the tooling and stone holders have a life span and don't last forever and guys that do stone jobs don't believe this most of the time cause the replacements are costly and till they start checking runout they won't believe it.

Doing good seat work is an art form that takes years to master with a stone setup but anything worth doing should always be done right the 1st time just like the valve guides need to be sized to each valve to be perfect.

You should think about getting a machine and investing in the tooling for the stuff you work on all the time. There is lots available that way after the word gets out you will need to upgrade

[Amilcar]

Here's an example of what I mean. Seat cut with neways. Nice and shiny all round. I mark the seat with black ink and lap the valve to check seating. Result is in the picture. If I continue cutting it does the same thing.
Cutter is 45* as is valve in this instance.
I'd like to hear people's thoughts and experience with the neways.

You have 2 or maybe 3 main reasons its not working.

- The new guides are not concentric with the seats.
By the time you start to cut, the minor flex of the pilot, allows the cutter remove material from where it shoud not.

- By nature, these cutters put a lot more side load on the pilot than grinding process.
A tappered/ expandable pilot will never be the best option to work that way. Its impossible to have such type of pilot being guided by the far most important guide region, both far ends of it. (pilot will wiggle)

- Guides being not perfectly straight and a expandable/ tappered pilot maybe will align at whatever region on the guide that will not be concentric with the seats.


I have neways and have being thru all kind of nightmares it would provide. With soft seats, its doable with a lot of practice. The less load you put downward, the better the outcome, ALWAYS.
I use it mainly to rough cut for larger valves with plain straight pilots( 5-6 for each guide size) and fine finish with stones.
The straight pilots help me alot even with the stones getting less variations from heads to heads
-

[simon010]

maybe a solid pilot might help ?

https://goodson.com/collections/pilots

anyone make a good carbide pilot for the neway cutters ?

rgds
sdo

[modok]

what size is the pilot?
Most are 3/8, but you can also get neway cutters to fit .385 pilots, and other sizes as well.
Neway brand pilots are not great, but they are also cheap, so it's kinda ok

[larrycavan]

It's like any tool on the planet, it's all in the hands of the user. Yes, you can cut concentric seats with Neway cutters. Yes it's time consuming. Yes, expandable pilots are about useless. A power head is far better than a T handle but you can get by.

The one thing you never want to do is cut over an existing seat cut. Take it completely out with your inside & top cutter, then cut the 45. Put your preferred dye on the seat, then lightly spin the 45 with your fingers to see if you still have a high spot. It will show up straight away. Once you have the seat cutting all the way around you can finish the valve job.

Use a blue permanent marker to color up the finished seat, get it good and wet. Then pop the valve in, give it light pressure, turn it back and forth a few degrees with a lapping stick, pull it out and examine the valve. Done correctly the marker will transfer to the face of a clean valve. NOTE: If you have a 46 cutter an a 45 valve face, the actual lapped in seat line will be slightly lower than what the marker shows you. So, for example if you want to push the 45 out, leaving only a thin, shiny line above it, then you'll want the marker to show all the way to the edge of the valve face.

Hard seats are tough and take more time. Del Rio Machine sells some nice cutting aggressive blades for Neway cutters. They're on Ebay uner 3A Cut. They also have the 3 angle cutting blades for Neway cutters. Those work best in an actual seat and guide machine vs a Neway Power Head.

Install the valve in the port and tap on valve with your finger. If it clicks...it's not straight. You have work to do yet. If you happen to have a mandrel and a 45 stone, you can quickly true up a seat by spinning the stone by hand.

[larrycavan]

Here's an example of what I mean. Seat cut with neways. Nice and shiny all round. I mark the seat with black ink and lap the valve to check seating. Result is in the picture. If I continue cutting it does the same thing.
Cutter is 45* as is valve in this instance.
I'd like to hear people's thoughts and experience with the neways.

That photo shows 2 possible things happening.

the untouched area is the low spot.

1 - you have not cut enough yet
2 - it's possible to rock the cutter with a T handle and get a result like that.

[AC sports]

Thanks for your input. After a very long time I finally cut and lapped the seats with the valves. It definitely helps to do the 70* throat then the 30* top cut first until they meet. Then the 45* seat cuts easier and with less pressure. It wasn't concentric first go, but playing with the pilot etc eventually got me there. I'd definitely not recommend the expanding pilot set up.

[dynodarrell]

i have the overhead rack for Neway. I have seen the seat condition many times. in my experience , it definitely helps to pay attention to that bottom angle/ cut. it seems to take the load off of the 45 cut especially when going to over sized valves. I also use a stone on the 45 to touch up on the tough ones. I drive the stone with the overhead rack lightly. carbide solid pilot , always. Hope this helps. This is mostly 4.5 to 5.5 mm bike heads, which are large dia. for small stems. 26 to 34mm dia.

[larrycavan]

Thanks for your input. After a very long time I finally cut and lapped the seats with the valves. It definitely helps to do the 70* throat then the 30* top cut first until they meet. Then the 45* seat cuts easier and with less pressure. It wasn't concentric first go, but playing with the pilot etc eventually got me there. I'd definitely not recommend the expanding pilot set up.

Decades ago when I first started I only had the setup you have now and struggled with the expanding pilot. there's just not enough surface area for the expanded portion to get it truly centered. Solid pilots make all the difference. Glad you nailed it

[cjperformance]

Neway cutters are an art to use properly. Realistically they are far from ideal. I have done what feels like a trillion seats (in the past) with neways, anyrhing from a touchup to fitting hardened exhaust seats and cutting that hardened stellite seat from a blank out to a finished valve size, with neways, by hand!! Not to sing my own song but I learned how to get seats spot on with them , the hard way.

-You need a correctly sized and aligned guide.

-The pilot must be in good condition and preferably use a sized pilot NOT a multi size/expandable pilot.

-The end of the guide in the bowl area must be cut true with the guide, if it is on any angle an expandable pilot is useless and even the best fitting straight pilot then requires to be held up off of the angle at the end of the guide face.

-You need to 'read/feel' what the cutter does AS SOON AS YOU START CUTTING. if you dont it will lead to you chasing the seat in your pic.

- Feel / Look at where the cutter cuts material using 1 very light revolution.

-If the cutter tags the seat at say 12 o clock, you need to put the slightest pressure toward 12 o clock AND, to stop cutting load dragging the cutter into the seat back toward 11 o'clock you need to put light pressure over toward 1/2 oclock aswell.

-Cut 2 or 3 revolutions only, look at where its cutting, as soon as you have some seat all way round the seat area get a valve in there (or concetricity gauge) and with NO lube in a clean guide, feel the valve on the seat, when the seat is not concentric, the valve head will tilt off center and the dry guide makes the valve stick slightly on the seat, with a keen eye and feel you can find the area of the seat that is highest/closest to guide center, and lightly cut using pressure toward and slightly forward of this spot.

-they are tedious, they take time , but you can get a spot on seat with practice.

- your cutting pressure is not always inline with the guide, this is where people go wrong, these cutters will follow a non concentric seat and lead you astray, feel is what you need to practice.

-canted valve heads are great practice as you need to work with cutting pressure in different planes.

- work slow, work light, keep the seat clean of cutting debris or just as you have a seat almost right a bit of swarf will catch up in a cutter and score the seat, especially with hardened seats.

-stagger the cutters in the holder very slightly, the angled cutter ridges help prevent any undulations in the seat but with hardened seats staggering the cutters a little really is one thing that makes a big difference.

-once you get the feel for using pressure in the correct direction and feeling the valve on the cut seat you will find that you can actually pick when the seat is concentric to well withing the guide to stem clearance and you get to know when to not even bother trying to lap as it wont work AND you know a seat 'feel' that will lap instantly- after which you will likely stop lapping because you dont really need to anymore.

-get a junk head, deliberatly cut using pressure off to one side for several revolutions and feel the valve on the seat, lap it to see what you feel, then use pressure as i described to fix the seat. You will see what i mean.

[Boomtastic AL]

Well this is just magical, was googling neway vs stone and found a discussion for the PRECISE problem i was having. Notes Craig provided are very helpfull, but this got me considering a stone setup.

Another user here said to do two other angles to remove 45 to a minimum, which i see how it would help but wouldn't that cut too much off the seat(i should say more than if you didnt do that).

How much different would the result be if OP used stone on that cut, would it still happen? I would imagine if tapered pilots on same setup you'd still have stone follow old pattern or not?

Thanks for any input!

[cjperformance]

Wow old thread popped up. Fear not, stones can destroy seats just a well as neway cutters can and even the best machines can get seats wrong. As long as the equipment is in good condition its simply up to operator skill. I've seen good and bad valve seats from neway cutters, stones and very expensive machines! It truly is all in the practice and skill of the operator.

[modok]

Sometimes it is better to narrow the seat and cut the seat angle last, If the seats are hard, taking too much pressure to cut.
if cutting too aggressive then can can be better to do the seat angle first then narrow it back down.
You don't have to narrow it all the way to nothing, just a different order of operation.

How you DRIVE the cutter and keep even pressure on it could make a big difference.
Or, there are 3 or 5 or seven blade ones, plain blades or serrated, must be some reason for all that.

I never tried anything besides a tee handle to drive them, but I've been told other ways of driving them will work better.
Don't necessarily need the whole official setup with the hanging motor and driveshaft. You could use some type of very light power drill on very low speed, or a very LONG speed wrench? maybe a windshield wiper motor. You should be able to get a small LOW rpm motor for cheap these days.

I have the telescoping tee handle driveshaft thingy, so I could use the neways with an old seat and guide machine to do the driving.
Still haven't tried it, but someday I will, if I can ever remember to try it. Could have tried it other day but Just didn't think of it.

When I was young and dumb neways just didn't work, but I'm smart enough to make them work now I think, except I forget to use them, because i've got about every valve seat cutting device known to man at my disposal.